(1) Field of the Invention
This invention relates to a technique for applying protective tape to a wafer surface with a pattern formed thereon and for separating the protective tape.
(2) Description of the Related Art
In a conventional process of manufacturing semiconductor wafers, a mechanical method such as grinding or polishing, or a chemical method including etching, is used to process the back surfaces of semiconductor wafers (hereinafter simply called “wafers”) to reduce the thickness thereof. When these methods are used to process the wafers, a protective tape is applied to the front surfaces of wafers in order to protect the front surfaces having wiring patterns formed thereon.
When a wafer is sent to a back-grinding process, the front surface (patterned surface) is suction-supported by a chuck table and the back surface is ground with a grinder. At this time, a protective tape is applied to the front surface to avoid the pattern being damaged under the stress of grinding occurring to the front surface, and to avoid contamination of the pattern.
The size of the protective tape applied to the surface of the wafer is, as shown in FIG. 1, smaller than the diameter of the semiconductor wafer. This is done to avoid a situation where, in time of a back grinding process, for example, protruding portions of the protective tape flutter and damage edges of the wafer.
The protective tape applied to the surface of the wafer in this way is separated in a separating step following the back grinding process.
However, the semiconductor wafer with the protective tape applied thereto and having undergone a back grinding process presents the following inconvenience.
As shown in FIG. 2, the semiconductor wafer formed thin by the back grinding process has sharp edges projecting from the portion covered by the protective tape. Thus, when the wafer is stored in a cassette, the edges stick into inner walls of the cassette. When the wafer is taken out of the cassette in such a state, the edges of the wafer may be broken, or a fetching error may be caused.